This invention relates to an optical disc drive and, in particular, relates to a focus control technique in irradiating a multilayer optical disc having a plurality of recording layers with a light beam to read or write information therein.
An optical disc drive that reads or writes information in an optical disc such as CD (Compact Disc), DVD (Digital Versatile Disc), and BD (Blu-ray Disc) spins an optical disc at high speed, irradiates an information recording surface of the spinning optical disc with laser light, and detects the reflection of the laser light to read or write information.
Regarding a focus jump control to move the focal point of a light beam to a different recording layer, JP2004-63025A discloses a technique to detect the distribution of recorded areas and unrecorded areas on an optical disc and control the focus jump so that the focus landing point will not be in an unrecorded area.